1996 Roadtrek 190 Versatile Steering Issue

Recently purchased 1998 Pleasureway Excel on Dodge chassis. Driving home in it gave me white knuckles with all the steering wheel manuvering it took to keep it in the lane. Since then, 6 weeks ago, I have replaced shocks, sway bar link bushings, steering damper and inflated tires from 54 lbs when i drove it home to 62 lbs. This made a noticable difference. It was suggested that I inflate rear airbags to 75 lbs, this helped greatly on two lane country roads at 55 mph.
Went for test ride today on interstate with light cross wind. Yup, white knucle time and reduce speed to 55mph. I have ideas of futher areas to check, I'll keep you all posted.